By the way i need to say something.I ask some source to learn lambda calculus,it is true i have an exam but it is not <span class="Apple-style-span" style="font-family: arial, sans-serif; font-size: 13px; border-collapse: collapse; ">the situation of the original enquirer.Because i have some wish to write functional programming to learn lambda calculus.İ am sorry but i have to meantion.This is not necessary to say (</span><span class="Apple-style-span" style="font-family: arial, sans-serif; font-size: 13px; border-collapse: collapse; ">(the situation of the original enquirer) .I aö student who make some computer science.I have a long way but in a day future i become computer scientist !!! Sorry for that mail.</span><br>
<br><div class="gmail_quote">On Tue, Aug 11, 2009 at 2:23 PM, Matthias Felleisen <span dir="ltr">&lt;<a href="mailto:matthias@ccs.neu.edu">matthias@ccs.neu.edu</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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On Aug 11, 2009, at 2:07 AM, Chris Stephenson wrote:<br>
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(Your student asks general questions, so he&#39;s getting general answers.)<div class="im"><br>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
But Barendregt&#39;s trick of renaming all bound variables to have different<br>
names from all free variables simplifies some proofs, but obscures the<br>
issue of scope for those who interested in Lambda calculus as a model<br>
for programming languages.<br>
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The phrase you&#39;re alluding to has been misunderstood by many many computer scientists. Due to copying it isn&#39;t enough to distinguish free/bound variables in the original term. You have to do so at every step of the reduction. Barendregt knows this as the Yellow book shows. Computer science papers seem to not understand this on occasion. So yes, you&#39;re right :-) Use de Bruijn indices.<br>
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-- Matthias</font><div><div></div><div class="h5"><br>
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